Heat-wing

ABSTRACT

A heat-wing includes: a sealed hollow chamber including two plates and a frame connecting the two plates; a capillary structure layer closely attached to an inner surface of the chamber; and a phase transition working medium sealed in the chamber. A portion of the frame or a portion of a periphery of one of the two plates serves as an evaporation area of the heat-wing, and the rest portion of the chamber serves as a condensation area of the heat-wing. The heat-wing has an increased vapor passage area, liquid working medium flow-back passage width and condenser heat transfer area and a reduced evaporator center-to-edge distance, and is hence capable of achieving a great improvement in heat transfer limit and heat flux density.

TECHNICAL FIELD

The present invention relates generally to phase-change heat exchangers,and particularly to a heat-wing and use thereof.

BACKGROUND

Compared to high thermal conductivity solid metal blocks, phase-changeheat exchangers have higher equivalent thermal conductivities and betterheat dissipation performance. They are widely used because of a varietyof advantages, such as a high thermal conductivity and good temperatureuniformity. These advantages are realized by liquid working media sealedin the heat exchangers, on the phase transition of which the heatexchangers rely for heat transfer. Currently, heat pipes and vaporchambers are two types of commonly used phase-change heat exchangers.

Referring to FIG. 1, a typical heat pipe is composed of a hollowcylindrical chamber 11, a capillary structure 12 and a phase transitionworking medium 13 hermetically sealed in the chamber. Fabrication of theheat pipe generally includes: vacuuming the chamber and partiallyfilling the chamber with the working medium 13; impregnating thecapillary structure 12, which is closely attached to an inner surface ofthe chamber 11, with the working medium 13; and sealing the chamber. Oneend of the heat pipe serves as an evaporation area 14 which is broughtin contact with a heat source for extracting heat from the source, whilethe other end acts as a condensation area 15 for dissipating heat,directly, or with the aid of auxiliary equipment such as fans for ahigher efficiency. The rest section of the heat pipe between theevaporator and condensation areas 14 and 15 is referred to as anadiabatic section. When the evaporation area 14 is being heated, theworking liquid medium 13 in the capillary structure 12 vaporizes into avapor working medium 16. The vapor working medium subsequently flowsthrough ducts 17 under the action of a differential pressure and entersthe condensation area 15, where it condenses back to the liquid workingmedium 13, releasing the heat. Thereafter, the restored liquid workingmedium 13 flows along the capillary structure 12 under a capillarypressure and returns to the evaporation area 14. With the repetition ofthis cycle, heat 18 is continuously transferred from the evaporationarea 14 to the condensation area 15 and thereby realizes heatdissipation. However, as the heat pipe has a relatively small diameter,the vapor transport occurs therein in a nearly one-dimensional, linearmanner. Moreover, limited by the narrow ducts for vapor transport and aminimal flow-back passage width of the liquid working medium, the heatpipe tends to reach its heat transfer limit before operating at theoptimal performance level.

As an improved type of heat pipe, Chinese patent publication No.CN201364059Y discloses a vapor chamber, or called a flat plate heatpipe. As shown in FIG. 2, each of the vapor chambers 42 and 42′ uses itstwo plates to serve as working plates. In the vapor chamber, vapor istransported in a nearly two-dimensional, planar manner. Compared withheat pipe, the vapor chamber provides a larger vapor passage area and alarger liquid working medium flow-back passage width, thus ensuringbetter temperature uniformity than that of a heat pipe. However, duringuse of this kind of vapor chambers 42 and 42′, heat is transferredsuccessively through a heat conduction piece 41 and clamps 412 forfixing the vapor chambers which are arranged in a directionperpendicular to the plane of the heat source and finally reaches theplates of the vapor chambers 42 and 42′. In such a configuration, thedistance from the heat source to the vapor chambers is too long, with anaverage distance equal to a thickness of the heat conduction piece 41plus half of a height of the clamp, while a total heat conduction widthin the clamps 412 is too short, which is only a sum of the widths of thetwo clamps 412, thereby results in a relatively high thermal resistance.

Therefore, there exists a need for a novel phase-change heat exchangerwith a large vapor passage area, large working medium flow-back passagewidth and short evaporator center-to-edge distance.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide aphase-change heat exchanger with a large vapor passage area, largeworking medium flow-back passage width, short evaporator center-to-edgedistance, large condenser heat dissipation area and high heat transferlimit.

In pursuit of the above objective, a first aspect of the presentinvention provides a heat-wing, which includes: a sealed hollow chamber,including two plates and a frame connecting the two plates; a capillarystructure layer closely attached to an inner surface of the chamber; anda phase transition working medium sealed in the chamber.

Wherein, a portion of the frame or a portion of a periphery of one ofthe two plates is in direct contact with a heat source and therebyserves as an evaporation area of the heat-wing, and the rest portion ofthe chamber that is not in contact with the heat source serves as acondensation area of the heat-wing.

Wherein, each of a length and a width of the chamber is much greaterthan a thickness of the chamber.

In one preferred embodiment, materials that the chamber can befabricated from include copper, aluminum, stainless steel metal andalloys thereof, high thermal conductivity ceramics, and other highthermal conductivity materials.

In another preferred embodiment, the capillary structure layer may be asingle- or multi-layer structure made of sintered powder(s), wirelattices, grooves etched into the chamber, fibers, coated or growncarbon nanowalls, carbon nanotubes or carbon nanocapsules, other coatedor grown nano- or micro-order thin organic or inorganic layer(s), or anycombination of the above, or any other suitable structure providingcapillary attraction.

In a further preferred embodiment, materials that may be used as thephase transition working medium include water and other liquids, lowmelting point metals, carbon nanocapsules, other nanoparticles, mixturesof the above materials, and other materials having gas-liquid phasetransition at a temperature within the operating temperature range ofthe heat-wing.

In yet another preferred embodiment, the two plates are parallel orsubstantially parallel to each other.

In a further preferred embodiment, each of the plates may assume arectangular shape or any other shape, and may be flat or curved.

In yet a further preferred embodiment, the heat-wing has across-sectional area of a section near to the evaporation area that islarger than a cross-sectional area of an upper section of the heat-wing.Alternatively, the cross-sectional area of the section near to theevaporation area may also be smaller than or equal to thecross-sectional area of the top section.

In another preferred embodiment, the heat-wing may be evacuated to acertain degree of vacuum, and may accordingly further include a supportor connection structure disposed between the two plates according to themechanical strength of the chamber and positive and negative pressuresto be applied thereto.

In a preferred embodiment, the support or connection structure mayassume the shape of a dot, a line or a sheet.

In a further preferred embodiment, the heat-wing may further include afin.

In yet another preferred embodiment, the heat-wing and/or the fin may becoated with a black-body radiator material.

In a further preferred embodiment, the heat-wing may further include ahose for vacuuming and liquid filling.

In a preferred embodiment, an array of the heat-wings may be disposed ona heat source.

Another aspect of the present invention provides an apparatus whichincludes a heat-generating component and at least one heat-wing eachincluding: a sealed hollow chamber including two plates and a frameconnecting the two plates; a capillary structure layer closely attachedto an inner surface of the chamber; and a phase transition workingmedium sealed in the chamber, wherein each heat-wing has a portion ofthe frame or a portion of a periphery of one of the two plates thereofin direct contact with the heat-generating component and thereby servingas an evaporation area of the heat-wing, and the rest portion of thechamber that is not in contact with the heat-generating component servesas a condensation area of the heat-wing, wherein each of a length and awidth of the chamber of each heat-wing is much greater than a thicknessthereof.

Compared with the prior art, the present invention has the followingadvantages:

as the heat-wing of the present invention is a hermetically sealedplate-shaped hollow chamber having a length and width both much greaterthan its thickness, by bringing a portion of a periphery of one of thetwo plates or a portion of the frame, which has a limited area relativeto the whole chamber area, into contact with the surface of the heatsource so as to make it serve as an evaporation area, vapor istransported in a nearly two-dimensional, planar manner in the heat-wing,which results in a large passage area for vapor transport and ensures ahigh temperature uniformity;

since the gap between the two plates is very small, a very shortevaporation area center-to-edge distance can be achieved, therebyaddressing the issue of early dry-out of the evaporation area centralarea;

by using the two relatively large plates as a condensation area, theheat-wing ensures an extremely large condensation area which facilitatesthe heat dissipation, and provides a large working medium flow-backpassage width which is about two times the width of the heat-wing andallows a large flux of the working medium.

The heat-wing has a greatly improved heat transfer limit and is hencecapable of achieving a higher heat flux density over the prior art.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic cross-section view of a conventional hot pipe.

FIG. 2 shows a schematic cross-section view of a conventional vaporchamber.

FIG. 3 shows a three-dimensional view of a heat-wing in accordance witha first embodiment of the present invention.

FIG. 4 shows a schematic cross-sectional view taken along the line A-Aof FIG. 3.

FIG. 5 shows a schematic cross-sectional view of a heat-wing inaccordance with a second embodiment of the present invention.

FIG. 6 shows a schematic cross-sectional view of a heat-wing inaccordance with a third embodiment of the present invention.

FIG. 7 shows a schematic cross-sectional view of a heat-wing inaccordance with a fourth embodiment of the present invention.

FIG. 8 shows a schematic cross-sectional view of a heat-wing inaccordance with a fifth embodiment of the present invention.

FIG. 9 shows a schematic cross-sectional view of a heat-wing inaccordance with a sixth embodiment of the present invention.

FIG. 10 shows a three-dimensional view of a heat-wing array inaccordance with a seventh embodiment of the present invention.

FIG. 11 shows a schematic cross-sectional view of a heat-wing array inaccordance with an eighth embodiment of the present invention.

FIG. 12 is an exploded three-dimensional view of FIG. 11.

DETAILED DESCRIPTION

The forgoing objectives, features and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments thereof, which is to be read in connectionwith the accompanying drawings. It is to be understood that theinvention is not limited to the embodiments described herein and theembodiments are provided to enable those skilled in the art tounderstand the present invention. In addition, the technical terms usedherein could be construed in the broadest sense without departing fromthe spirit and nature of the invention. The use of the same referencesymbols in different drawings indicates similar or identical items.

A first embodiment of the present invention is shown in FIGS. 3 and 4.As illustrated, the heat-wing of the present invention includes achamber 2 which is essentially a hollow plate-shaped structure includingtwo plates 21 and a frame 22 and 23 connecting the two plates 21. Theheat-wing further includes a capillary structure layer 12 which isclosely attached to an inner surface of the chamber 2, and a phasetransition working medium 13 hermetically sealed in the chamber 2. Aportion of the frame 22 and 23, such as a portion of the bottom framesection 23 comes in contact with a heat source 3, and thus functions asan evaporation area, while the rest portion of the chamber 2 acts as acondensation area. Alternatively, it is also possible to use a portionof a periphery of one of the two plates 21 to serve as the evaporationarea.

Each of a length and a width of the heat-wing is much greater than athickness of the heat-wing. As a result, the heat-wing possesses a largepassage area for vapor transport, ensuring high temperature uniformity.Additionally, since the gap between the two plates 21 (i.e., thethickness of the heat-wing) is very small, bringing a portion of aperiphery of one plate 21 or a portion of the frame 23, which has alimited area relative to the whole area of thin plate-shaped chamber 2,into direct contact with the heat source 3 so as to make it serve anevaporation area realizes a very short evaporator center-to-edgedistance, thereby addressing the issue of early dry-out of theevaporation area central area. Moreover, by using the two relativelylarge plates of the chamber to serve as a condensation area, theheat-wing ensures a large condensation area, which facilitates heatdissipation and vapor condensation. In addition, this feature allows alarger passage width for the flow-back of the working medium 13 andhence increases the flux of the medium. For these reasons, the heat-winghas a greatly improved heat transfer limit and is hence capable ofachieving a higher heat flux density.

Herein, the length of the heat-wing, i.e., the length of the hollowchamber 2, is defined as a dimension projecting away from a plane of theheat source, i.e., the length is a distance from a side of the plate 21contacting the heat source 3 to the opposite side of the plate 21 whichis farthest from the heat source 3. Therefore, for a flat plate 21(e.g., that shown in FIG. 8), the distance is the length of a straightline, and for a curved plate 21 (e.g., those shown in FIGS. 4 to 7, and11), the distance is the length of a curve. The width of the heat-wing,i.e., the width of the hollow chamber 2, is defined as a dimensionextending in parallel to the plane of the heat source, i.e., the lengthof each plate 21 extending perpendicular to the planes of FIGS. 4 to 8,and 11. Furthermore, a periphery of the plate 21 refers to an areaextending from the edge of the plate toward the center of the plate by avery short distance relative to a length or a width of the plate. Take asquare flat plate as an example, the periphery of such a plate is ahollow square extending from the four sides of the plate by a very shortdistance toward the center of the plate, and the very short distanceshould be much smaller than the side length of the square flat plate. Ifthe plate is circular, then the periphery of the plate is ring shaped.Those skilled in the art shall appreciate that the periphery of theplate could have different shapes depending on the shape of the plate.

The length, width and thickness of the heat-wing may vary with specificneeds of different applications, but a common requirement for thesedimensions is that both the length and width should be much greater thanthe thickness, e.g., at least one order of magnitude greater. Thepresent invention is, however, not limited in this regard, because thoseskilled in the art may design suitable length, width and thickness forthe heat-wing without departing from the spirit of the presentinvention, based on their knowledge.

Materials that the chamber 2 can be fabricated from include copper,aluminum, stainless steel and alloy thereof, high thermal conductivityceramics, and other high thermal conductivity materials, each of whichcan ensure a good heat transfer performance of the heat-wing.

The capillary structure layer 12 may be a single- or multi-layerstructure made of sintered powder(s), wire lattices, grooves etched intothe chamber, fibers, coated or grown carbon nanowalls, carbon nanotubesor carbon nanocapsules, other coated or grown nano- or micro-order thinorganic or inorganic layer(s), or any combination of the above, or anyother suitable structure providing capillary attraction.

Materials that may be used as the working medium 13 sealed in theheat-wing include water and other liquids, low melting point metals,carbon nanocapsules, other nanoparticles, mixtures of the abovematerials, and other materials having gas-liquid phase change at atemperature within the operating temperature range of the heat-wing.

The heat-wing may be evacuated to a certain degree of vacuum, and mayaccordingly further include a support or connection structure (notshown) disposed between the plates 21. The support or connectionstructure may be designed according to the mechanical strength of thechamber 2 and positive and negative pressures to be applied thereto. Thesupport or connection structure may assume the shape of a dot, a line, asheet or any other shape. Further, in some alternative embodiments inwhich the chamber 2 has a sufficient strength to sustain the requiredload, the heat-wing may not include the support or connection structure.

In the first embodiment, the two plates 21 are in parallel to each otherexcept in their bottom sections, and a bottom section of the chamber 2that is in close contact with the heat source 3 is thicker than an uppersection of the heat-wing. In some alternative embodiments of theinvention, the plates 21 may be entirely parallel to each other, or thechamber 2 may have different thicknesses in its top and bottom sections.

The heat-wing may further include auxiliary features arranged on theplates, such as, for example, fin(s) (not shown), hose(s) for vacuumingand liquid filling (not shown) and the like. The fin(s) is capable offacilitating the dissipation of heat from the interior of the heat-wing.In addition, for a better heat transfer performance, the heat-wingand/or the fin(s) can be coated with a black-body radiator material inorder to further promote heat dissipation from the interior of theheat-wing and fin(s). The hose(s) can be used in creating a desiredvacuum condition for the working medium in the heat-wing. It is to benoted that the heat-wing may not include the fin(s) and hose(s) in somealternative embodiments.

Heat-wings constructed in accordance with second to sixth embodiments ofthe invention are respectively shown in FIGS. 5 to 9. As demonstrated inFIGS. 5 to 7, the heat-wing of the present invention may have differentcross-sectional shapes of a bottom section thereof, such as, a convexarc shape of a bottom section of the plate 21 proximal to theevaporation area shown in FIG. 5, a concave arc shape shown in FIG. 6,and a substantially rectangular shape shown in FIG. 7. In addition, thebottom section of the chamber may be slightly thicker than the topsection of the heat-wing. Alternatively, it can be appreciated that thebottom section of the heat-wing may also have a thickness the same orsmaller than that of the top section of the heat-wing.

As demonstrated in FIGS. 4 to 9, the frame of the heat-wing may eitherinclude a bottom frame section, two lateral frame sections and a topframe section (as shown in FIGS. 4 to 7, and 9), or only includes abottom frame section and two lateral frame sections but no top framesection (as shown in FIG. 8). In the latter case, the hollow chamber maybe closed at the top by directly connecting top portions of the twoplates 21. Further, as shown in FIGS. 4 to 7, and 9, the top framesection 22 may be closed by different techniques and thus have differentshapes, such as, for example, an arc shape shown in FIG. 5, a linearshape shown in FIG. 6, and a shape with a protrusion which may be formedat different positions as shown in FIGS. 7 and 9.

As demonstrated in FIGS. 5 to 9, and 11, the heat-wing may have avariety of overall shapes, such as, for example, the shape of a wedge asshown in FIG. 8 and the shapes with bent plates 21 as shown in FIGS. 6and 7.

In addition, as demonstrated in FIG. 9, the heat-wing may have a portionof a periphery of one plate 21 being taken in contact with the heatsource 3 to serve as the evaporation area.

Further, as demonstrated in FIG. 11, the heat-wing may be bent toproject laterally in response to a height limitation.

FIG. 10 shows a seventh embodiment of the present invention. Asillustrated, in this embodiment, a plurality of the heat-wings of FIG. 3are arranged in an array and disposed on a heat source, totally coveringthe top surface of the heat source. Such array arrangement expands thetwo-dimensional phase-change heat transfer into a three-dimensionalspace and hence can achieve a higher heat flux density.

FIGS. 11 and 12 show an eighth embodiment of the present invention. Asillustrated, in this embodiment, a plurality of the J-shaped heat-wingsof FIG. 7 are arranged in an array and disposed on a heat source,totally covering the top surface of the heat source. Differing from theseventh embodiment, each heat-wing of the array of this embodiment isbent to project laterally from the heat source and is thus particularlysuitable for applications where there exists a height limitation.

It is to be understood that changes and modifications may be made bythose having ordinary skill in the art after reviewing the abovedescription. It is therefore intended that the appended claims cover allsuch changes and modifications that are within the scope of the claimedsubject matter.

INDUSTRIAL APPLICABILITY

The heat-wing of the present invention can be applied in any apparatusincluding a heat-generating component needing heat dissipation, simplyby bringing a portion of a periphery of one plate 21 or a portion of theframe 22 and 23 in direct contact with the surface of theheat-generating component to make it serve as an evaporation area. Asthe heat dissipation mechanism of the heat-wing has been explainedabove, further description of it is omitted here.

The application of the present invention in industries can not onlygreatly reduce the dimension and height of heat dissipation apparatusesbut also highly improve the heat flux density of heat dissipationapparatuses.

Heat dissipation apparatuses incorporating the heat-wing(s) can be usedfor the heat dissipation of high-power semiconductor devices likehigh-power transistors, high-power semiconductor laser devices,high-power light emitting diodes (LEDs), high-power central processingunits (CPUs), high-power graphics processing units (GPUs) and so on.

In occasions where heat dissipation apparatuses incorporating theheat-wing(s) is used, all water cooling methods can be replaced by aircooling methods, and active cooling methods can be replaced by passivecooling methods.

Heat dissipation apparatuses incorporating the heat-wing(s) can enablethe reduction of height of a tower case of a desktop computer to nearlya thickness of a laptop computer.

In order for a better understanding of the high heat dissipationperformance of the heat-wing of the present invention and itsapplication prospect in the heat transfer field, comparisons are madebetween conventional heat pipe and vapor chamber and the heat-wing ofthe present invention.

Comparison Between Heat-Wing and Conventional Heat Pipe

The exemplified conventional heat pipe is a commonly used Φ6 mm×200 mmheat pipe with an evaporation area, having a width of about 4 mm and incontact with a heat source. The heat-wing has a thickness of 6 mm, awidth of 100 mm, a height of 100 mm, and also an evaporation area widthof 4 mm. A central processing unit (CPU) with a typical size of 35 mm×35mm, the most common kind of device needing heat dissipation, isexemplified as the heat source. Therefore, both the heat pipe and theheat-wing have an evaporation area of 4 mm×35 mm.

The performance of the two heat dissipaters was assessed on thefollowing five metrics:

1. Boiling limit: If the radial heat flux density in the evaporationarea of the heat pipe becomes too high, the liquid in the evaporatorwick boils. And when the radial heat flux density reaches a thresholdvalue, across a long length from the adiabatic section to the end of theevaporation area, the liquid in the evaporator wick is in a criticalboiling state and generates a great amount of bubbles which blocks wickpores, thus reducing or destroying the capillary attraction of the wick.This causes the amount of the liquid flowing back to the evaporationarea to be lower than its amount evaporated therein per unit time. As aresult, the end of the evaporation area is dried out, thus partiallydisabling the evaporation area.

Compared to the heat pipe which has the length from the adiabaticsection to the end of the evaporation area, i.e., the length the workingfluid is transported, of 35 mm, thanks to the two plates which functionsnot only as a condensation area but also as a means for liquidtransport, the length of the heat-wing from the adiabatic section to thecenter of the evaporation area is 2 mm. That is, a maximum liquidtransport length of the heat-wing is 2 mm, lower than 6% of that of theheat pipe. Therefore, the heat-wing is nearly immune from the boilinglimit issue.

2. Sonic limit: The flowing behavior of vapor in the heat pipe issimilar to that of gas in a De Laval nozzle. When the evaporation areaof the heat pipe is kept at a certain temperature, lowering thetemperature of the condensation area can result in an increase in thevapor velocity and hence an increase in the heat transfer rate. However,when the velocity of vapor exiting the evaporation area increases to ashigh as the local speed of sound, it will not increase any more to leadto further rise in the heat transfer rate, even upon the condensationarea temperature being further lowered. This choked flow condition iscalled the sonic limitation.

Compared to the heat pipe which has a vapor exit area of the evaporationarea (i.e., the inner cross-sectional area of the heat pipe) of 12 mm²,the evaporator vapor exit of the heat-wing is a hollow space flaringfrom a semicircle with an area of about 210 mm² (35 mm×3.14/2×4), higherthan 1750% of the 12 mm² of the heat pipe, let alone that the crosssectional area of the space proportionally increases with the lengthoutwardly from the semicircle. Therefore, the heat-wing has no limit forvapor flux and it is hence immune from the sonic limit issue.

3. Entrainment limit: In the heat pipe, the vapor and liquid move inopposite directions and hence confront at the liquid-vapor interface.Under the action of the oppositely flowing vapor, the surface of theliquid waves, and at a high vapor velocity, the surficial liquid will besheared into small droplets and entrained into the vapor flowing towardthe condensation area. If the entrainment becomes too great, the liquidflowing back to the evaporation area will be insufficient in amount oreven be cut off halfway in the wick, thus leading to dry-out of theevaporation area and operation cessation of the heat pipe. The heattransfer rate at which this occurs is called the entrainment limit.

As described above, compared to the vapor passage area of the heat pipewhich is 12 mm², that of the heat-wing is a hollow space with asemicircular cross sectional area proportionally increasing outwardlyfrom an area of about 210 mm², higher than 1750% of that of the heatpipe. Therefore, for the same condition, the vapor flux and heat fluxdensity in the adiabatic and condensation areas of the heat-wing aremuch lower than 6% of those of the heat pipe and the heat-wing is hencefree from the entrainment limit issue.

4. Capillary limit: during the operation of the heat pipe, when the sumof the liquid and vapor pressure drops equates to the maximum capillarypressure that the wick can sustain, the heat pipe reaches its maximumheat transfer capacity. In this situation, any attempt to increase theevaporation or condensation rate will cause an insufficient supply ofliquid to the evaporation area due to an insufficient capillarypressure. As a result, the amount of the liquid supplied to theevaporation area is lower than the amount of the liquid evaporatedtherein per unit time, thus leading to the dry-out and overheating ofthe evaporation area. In a serious case, within a short time, the wallof the heat pipe will be increased to such a high temperature as tocause burnout.

At the same capillary pressure, the wick width (equivalent to the liquidsupply diameter) of the heat pipe for liquid transport toward theevaporation area is equal to its cross-sectional inner perimeter that is12 mm (not with wall thickness), while the minimum wick with of theheat-wing is 110 mm (35 mm×3.14), higher than 900% of that of the heatpipe. Further, the liquid transport occurs in the heat-wing in a mannerof converging through a circular space toward the central evaporationarea. Therefore, it is nearly impossible for the heat-wing to reach acapillary limit.

5. Condenser limit: The condenser limit refers to the maximum heattransfer rate achievable at the vapor-liquid interface in thecondensation area of the heat pipe. The maximum heat transfer capabilityof the heat pipe may be limited by the condensing capacity of thecondensation area which is proportional to the surface area thereof.

Compared to the condensation area surface area of the heat pipe that is3100 mm² (6 mm×3.14×165 mm), that of the heat-wing is 20000 mm² (100mm×100 mm×2), 700% of that of the heat pipe.

It can be understood from the foregoing description that particularsubstantive features of the heat-wing of this invention are a bettertemperature uniformity in the evaporator and condensation areas, lowsurface temperature of the heat source, and two orders of magnitudehigher heat flux density sustainability, which are realizable under thesame operating condition as the heat pipe. In the heat transfer field,this is a great breakthrough comparable to the invention of the firstheat pipe. Since the advent of the phase-change heat transfer theory,its primary application has been still being limited to itsprototype—heat pipes. The heat-wing disclosed herein is a novel productof the theory which has an unprecedented working mechanism. It willgreatly promote the application of the phase-change heat transfertheory.

For example, as the performance of CPUs is proportional to their powerconsumption, the pursuit for higher CPU performance is always frustratedby the increased heat caused by a proportional rise in the powerconsumption. This necessitates the employment of heat dissipaters thatcan sustain a higher heat flux density. Therefore, conventionalhigh-performance computers are all desktop computers equipped with ahuge tower case for accommodating a huge heat-pipe heat dissipater, andthus have a very limited transportability. In contrast, if the heat-wingof the present invention is used, as shown in FIGS. 11 and 12, thethickness of the heat dissipater will be greatly reduced to 2-3 cm. Thiswill eliminate the huge tower case and enable the construction of ahigh-performance computer with the same thickness as current all-in-onecomputers, or even as relatively thick laptop computers.

Comparison Between Heat-Wing and Conventional Vapor Chamber

It is known to those skilled in the art that the effective thermalconductivity of phase-change heat transfer is 3 orders of magnitudehigher than that of solid mediums. Therefore, in the design of phasechange heat exchangers, it is essential to minimize the length of theheat conduction medium between the phase change heat exchanger and theheat source.

When using the conventional vapor chamber as shown in FIG. 2, heat istransferred successively through the heat conduction piece 41 and clamps412 which are arranged in a direction perpendicular to the plane of theheat source and finally reaches the plates of the vapor chambers 42 and42′. In such a configuration, the distance from the heat source to thevapor chambers is too long, which is a thickness of the heat conductionpiece 41 plus half of a height of the clamp, while a total heatconduction width in the clamps 412 is too short, which is only a sum ofthe widths of the two clamps 412, thereby results in a relatively highthermal resistance. While in the heat-wing of the present invention(e.g. the configuration shown in FIGS. 3 and 4), the frame section 23 isin parallel with the plane of heat source and brought in direct contactwith the heat source. Therefore, the distance from the heat source tothe phase transition working medium is merely a thickness of the framesection, and the heat conduction width is equal to the width of the heatsource. Compared with the conventional vapor chamber, the heat-wing ofthe present invention has greatly reduced the length of or eveneliminated the heat conduction medium between the phase change heatexchanger and the heat source, and hence has greatly lowered the thermalresistance. It is a similar occasion with the configuration shown inFIG. 9 where a portion of a periphery of one plate is brought in directcontact with the heat source, and thereby can achieve the same technicaleffects.

What is claimed is:
 1. A heat-wing, comprising: a sealed hollow chamber,including two plates and a frame connecting the two plates; a capillarystructure layer closely attached to an inner surface of the chamber; anda phase transition working medium sealed in the chamber, wherein aportion of the frame or a portion of a periphery of one of the twoplates as an evaporation area is in direct contact with a heat source,and the rest portion of the chamber as a condensation area is not incontact with the heat source; wherein each of a length and a width ofthe chamber is much greater than a thickness of the chamber.
 2. Theheat-wing of claim 1, wherein the two plates are parallel orsubstantially parallel to each other.
 3. The heat-wing of claim 1,further comprising a support or connection structure disposed betweenthe two plates.
 4. The heat-wing of claim 3, wherein the support orconnection structure assumes a shape of a dot, a line or a sheet.
 5. Theheat-wing of claim 1, wherein a portion of the frame as an evaporationarea is in direct contact with the heat source, and the rest portion ofthe chamber extends away from the heat source.
 6. The heat-wing of claim1, wherein a portion of the periphery of one of the two plates as anevaporation area is in direct contact with the heat source, and the restportion of the chamber extends away from the heat source.
 7. Theheat-wing of claim 1, wherein the two plates are flat or curved.
 8. Theheat-wing of claim 1, wherein the chamber is fabricated from a materialselected from a group consisting of copper, aluminum, stainless steelmetal and alloys thereof, high thermal conductivity ceramics, and otherhigh thermal conductivity materials.
 9. The heat-wing of claim 1,wherein the capillary structure layer is made of sintered powder(s),wire lattices, grooves, fibers, coated or grown carbon nanowalls, carbonnanotubes or carbon nanocapsules, other coated or grown nano-order ormicro-order thin organic or inorganic layer(s) or any combination of theabove.
 10. The heat-wing of claim 1, wherein the capillary structurelayer is a single-layer structure or a multi-layer structure, or anyother suitable structure providing capillary attraction.
 11. Theheat-wing of claim 1, wherein the phase transition working medium isselected from a group consisting of water and other liquids, low meltingpoint metals, carbon nanocapsules, other nanoparticles, mixtures of theabove materials, and other materials having gas-liquid phase transitionat a temperature within the operating temperature range of theheat-wing.
 12. The heat-wing of claim 1, wherein each of the two platesassume a rectangular shape or any other shape.
 13. The heat-wing ofclaim 1, wherein the chamber has a cross-sectional area of a sectionnear to the evaporation area that is larger than, equal to or smallerthan a cross-sectional area of an upper section of the chamber.
 14. Theheat-wing of claim 1, wherein the heat-wing can be evacuated to acertain degree of vacuum.
 15. The heat-wing of claim 1, furthercomprising one or more fins.
 16. The heat-wing of claim 15, wherein thechamber and/or the one or more fins is coated with a black-body radiatormaterial.
 17. The heat-wing of claim 1, further comprising a hose forvacuuming and liquid filling.